The growth plate, also known as the epiphyseal plate or physis, is the area of growing tissue near the ends of the long bones in children and adolescents. Each long bone has at least two growth plates: one at each end. The growth plate determines the future length and shape of the mature bone. When growth is complete—sometime during adolescence—the growth plates close and are replaced by solid bone.
Because the growth plates are the weakest areas of the growing skeleton—even weaker than the nearby ligaments and tendons that connect bones to other bones and muscles—they are vulnerable to injury. Injuries to the growth plate are called fractures.
Growth plate injuries can occur in growing children and adolescents. In a child, a serious injury to a joint is more likely to damage a growth plate than the ligaments that stabilize the joint. Trauma that would cause a sprain in an adult might cause a growth plate fracture in a child.
Growth plate fractures occur twice as often in boys as in girls, because girls’ bodies mature at an earlier age than boys. As a result, their bones finish growing sooner, and their growth plates are replaced by stronger, solid bone.
Growth plate injuries often occur in competitive sports such as football, basketball, or gymnastics, or as a result of recreational activities such as biking, sledding, skiing, or skateboarding.
Fractures can result from a single traumatic event, such as a fall or automobile accident, or from chronic stress and overuse. Most growth plate fractures occur in the long bones of the fingers (phalanges) and the outer bone of the forearm (radius). They are also common in the lower bones of the leg (the tibia and fibula).
Growth plate injuries can be caused by an event such as a fall or blow to the limb, or they can result from overuse. For example, a gymnast who practices for hours on the uneven bars, a long-distance runner, and a baseball pitcher perfecting his curve ball can all have growth plate injuries.
Although many growth plate injuries are caused by accidents that occur during play or athletic activity, growth plates are also susceptible to other disorders, such as bone infection, that can alter their normal growth and development. Other possible causes of growth plate injuries include the following:
A child who has persistent pain, or pain that affects athletic performance or the ability to move and put pressure on a limb, should never be allowed or expected to “work through the pain.” Whether an injury is acute or due to overuse, it should be evaluated by a doctor, because some injuries, if left untreated, can cause permanent damage and interfere with proper growth of the involved limb.
The doctor will begin the diagnostic process by asking about the injury and how it occurred and by examining the child. The doctor will then use x rays to determine if there is a fracture, and if so, the type of fracture. Often the doctor will x ray not only the injured limb but the opposite limb as well. Because growth plates have not yet hardened into solid bone, neither the structures themselves nor injuries to them show up on x rays. Instead, growth plates appear as gaps between the shaft of a long bone, called the metaphysis, and the end of the bone, called the epiphysis. By comparing x rays of the injured limb to those of the noninjured limb, doctors can look for differences that indicate an injury.
Very often the x ray is negative, because the growth plate line is already there, and the fracture is undisplaced (the two ends of the broken bone are not separated). The doctor can still diagnose a growth plate fracture on clinical grounds because of tenderness of the plate. Children do get ligament strains if their growth plates are open, and they often have undisplaced growth plate fractures.
Other tests doctors may use to diagnose a growth plate injury include magnetic resonance imaging (MRI), computed tomography (CT), and ultrasound.
Because these tests enable doctors to see the growth plate and areas of other soft tissue, they can be useful not only in detecting the presence of an injury, but also in determining the type and extent of the injury.
Since the 1960s, the Salter-Harris classification, which divides most growth plate fractures into five categories based on the type of damage, has been the standard. The categories are as follows:
The epiphysis is completely separated from the end of the bone or the metaphysis, through the deep layer of the growth plate. The growth plate remains attached to the epiphysis. The doctor has to put the fracture back into place if it is significantly displaced. Type I injuries generally require a cast to protect the plate as it heals. Unless there is damage to the blood supply to the growth plate, the likelihood that the bone will grow normally is excellent.
This is the most common type of growth plate fracture. It runs through the growth plate and the metaphysis, but the epiphysis is not involved in the injury. Like type I fractures, type II fractures may need to be put back into place and immobilized. However, the growth plate fracture heals a great deal, especially in younger children. If it is not too displaced, the doctor may not need to put it back into position. In this case, it will strengthen with time.
This fracture occurs only rarely, usually at the lower end of the tibia, one of the long bones of the lower leg. It happens when a fracture runs completely through the epiphysis and separates part of the epiphysis and growth plate from the metaphysis. Surgery is sometimes necessary to restore the joint surface to normal. The outlook or prognosis for growth is good if the blood supply to the separated portion of the epiphysis is still intact and if the joint surface heals in a normal position.
This fracture runs through the epiphysis, across the growth plate, and into the metaphysis. Surgery is frequently needed to restore the joint surface to normal and to perfectly align the growth plate. Unless perfect alignment is achieved and maintained during healing, prognosis for growth is poor, and angulation (bending) of the bone may occur. This injury occurs most commonly at the end of the humerus (the upper arm bone) near the elbow.
This uncommon injury occurs when the end of the bone is crushed and the growth plate is compressed. It is most likely to occur at the knee or ankle. Prognosis is poor, since premature stunting of growth is almost inevitable.
A newer classification, called the Peterson classification, adds a type VI fracture, in which a portion of the epiphysis, growth plate, and metaphysis is missing. This usually occurs with open wounds or compound fractures, and often involves lawnmowers, farm machinery, snowmobiles, or gunshot wounds. All type VI fractures require surgery, and most will require later reconstructive or corrective surgery. Bone growth is almost always stunted.
For all but the simplest injuries, your child’s doctor will probably refer him or her to an orthopaedic surgeon (a doctor who specializes in bone and joint problems in children and adults) for treatment. Some problems may require the services of a pediatric orthopaedic surgeon, who specializes in injuries and musculoskeletal disorders in children.
Treatment for growth plate injuries depends on the type of injury. In all cases, treatment should be started as soon as possible after injury and will generally involve a mix of the following:
The affected limb is often put in a cast or splint, and the child is told to limit any activity that puts pressure on the injured area.
If the fracture is displaced (meaning the ends of the injured bones no longer meet as they should), the doctor will have to put the bones or joints back in their correct positions, either by using his or her hands (called manipulation) or by performing surgery. Sometimes the doctor needs to fix the break and hold the growth plate in place with screws or wire. After the procedure, the bone will be set in place (immobilized) so it can heal without moving. This is usually done with a cast that encloses the injured growth plate and the joints on both sides of it. The cast is left in place until the injury heals, which can take anywhere from a few weeks to 2 or more months for serious injuries. The need for manipulation or surgery depends on the location and extent of the injury, its effect on nearby nerves and blood vessels, and the child’s age.
These are exercises designed to strengthen the muscles that support the injured area of the bone and to improve or maintain the joint’s ability to move in the way that it should. Your child’s doctor may recommend these after the fracture has healed. A physical therapist can work with your child and his or her doctor to design an appropriate exercise plan. Long-term followup is usually necessary to monitor the child’s recuperation and growth.
Most growth plate fractures heal without any lasting effect. Whether an arrest of growth occurs depends on the treatment provided, and the following factors, in descending order of importance:
The most frequent complication of a growth plate fracture is premature arrest of bone growth. The affected bone grows less than it would have without the injury, and the resulting limb could be shorter than the opposite, uninjured limb. If only part of the growth plate is injured, growth may be lopsided and the limb may become crooked.
Growth plate injuries at the knee have the greatest risk of complications. Nerve and blood vessel damage occurs most frequently there. Injuries to the knee have a much higher incidence of premature growth arrest and crooked growth.
